Most Baltic basin states, except Germany sort of, benefit by reduced reliance of Europe on Russian gas. Russia is constantly making threats to all of it's neighbours in that region but keeps discord in Europe via the gas blackmail. Similar story for Ukraine.
Western Europe - it's also not inconceivable. For example France is a net exporter of energy to Germany, and probably also doesn't like the Russian gas blackmail (while being less susceptible to it herself).
So literally anyone has some kind of incentive. Except perhaps Germany. You could still argue that Germany benefits in the long run as that reliance is bad for them, as it turns out, but it's harder to see them going cold turkey on themselves.
My bet is on India tough! /sarcasm
Please, stop speculating without any basis. You can make a case for basically anyone who trades gas or had any issues with Russia.
...is my point. I'm not speculating, merely saying basically anyone could benefit, so that alone tells you nothing.
Russia benefits if they can spin it as US action, as the damage to US alliance and trust relationships are huge and definitely strategic goals and gains for them. For a while in the beginning, when it wasn't clear that a functioning (but unused) pipeline remained, Russia was off the suspect list. But it turned out the sabotage missed a pipe and that fact keeps Russia high on the suspect list.
As for US, Germany had already given in to the US pressure and nixed the pipeline and made the gas deals. Why would US go and blow it up? It is possible, but makes little sense.
Whoever did this did so knowing that US will ultimately be blamed. Biden kinda set US up for that with veiled threats regarding NS before the Russian invasion. It's either Russia or UK/Ukraine, is my guess.